Enum Meta 

pub enum Meta {
    Unit,
    List(Vec<MetaExpr>),
    KeyValue(BTreeMap<Ident, MetaExpr>),
}

Represents the metadata provided as arguments to an attribute.

Variants

Unit

Represents empty metadata, e.g. @foo

List(Vec<MetaExpr>)

A list of metadata expressions, e.g. @foo(a, "some text", 0x01)

The list should always have at least one element, and this is guaranteed by the parser.

KeyValue(BTreeMap<Ident, MetaExpr>)

A set of uniquely-named metadata expressions, e.g. @foo(letter = a, text = "some text")

The set should always have at least one key-value pair, and this is guaranteed by the parser.

Implementations

impl Meta

pub fn borrow(&self) -> Option<BorrowedMeta<'_>>

Borrow the metadata without unwrapping the specific type

Returns None if there is no meaningful metadata

Trait Implementations

impl Clone for Meta

fn clone(&self) -> Meta

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl<I, V> From<I> for Meta

where Meta: FromIterator<V>, I: IntoIterator<Item = V>,

fn from(iter: I) -> Meta

Converts to this type from the input type.

impl<'a> FromIterator<(&'a str, MetaExpr)> for Meta

fn from_iter<T>(iter: T) -> Meta

where T: IntoIterator<Item = (&'a str, MetaExpr)>,

Creates a value from an iterator.

impl FromIterator<(Ident, MetaExpr)> for Meta

fn from_iter<T>(iter: T) -> Meta

where T: IntoIterator<Item = (Ident, MetaExpr)>,

Creates a value from an iterator.

impl FromIterator<MetaExpr> for Meta

fn from_iter<T>(iter: T) -> Meta

where T: IntoIterator<Item = MetaExpr>,

Creates a value from an iterator.

impl FromIterator<MetaItem> for Meta

fn from_iter<T>(iter: T) -> Meta

where T: IntoIterator<Item = MetaItem>,

Creates a value from an iterator.

impl PartialEq for Meta

fn eq(&self, other: &Meta) -> bool

Tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Eq for Meta

impl StructuralPartialEq for Meta